Role of Pleistocene climatic oscillations on genetic differentiation and evolutionary history of the Transvolcanic deer mouse Peromyscus hylocetes (Rodentia: Cricetidae) throughout the Mexican central highlands

Highlands are the most heterogeneous and complex biogeographic regions of Mexico. Species inhabiting these regions have been exposed to geologic events and climatic fluctuations in the past causing limited historical gene flow that resulted in structured genetic variation and high endemism. We examined the genetic variation of the mouse Peromyscus hylocetes throughout its geographic distribution within the Trans-Mexican Volcanic Belt (TVB), to estimate its current environmental suitability, habitat connectivity, and to reconstruct its evolutionary history by inferring the role of past events and abiotic factors. Two main genetic clusters corresponding to the west and east range of the species distribution were detected. Gene flow occurred largely from the west to the east cluster. Peromyscus hylocetes and P. aztecus diverged during the Pliocene-Pleistocene at the central-south region of the TVB. We hypothesized that after this divergence, P. hylocetes colonized the TVB during the Pleistocene and later expanded its distribution to the western TVB. Due to the climatic oscillations in the late Pleistocene, populations were restricted in western TVB during the warmer periods, and displacements occurred during colder periods from the west to the central TVB on several episodes.